1. Field of the Invention
The present invention generally relates to camera modules and, more particularly, to a camera module applied to a portable electronic device such as a mobile phone or a PDA (personal digital assistant).
2. Discussion of the Related Art
With the rapid development of multimedia technology, use of digital devices such as digital still cameras (“still cameras”) and digital video cameras (“video cameras”) has become wide-spread in many countries. Mobile phones have both improved in quality and in the number of functions they can perform. Therefore, digital devices performing a wide variety of function have been combined with mobile phones.
Consumers expect such still cameras and video cameras to provide high imaging quality. As with film-based cameras, the ability to zoom is a necessary function for achieving high image quality at large imaging distances. Generally, there are two kinds of zoom methods, an optical zoom and a digital zoom. Imaging quality tends to be much poorer when digital zooming is used than when using an optical zoom. Thus, in order to satisfy market demand, camera lenses of digital cameras should have an optical zoom function.
A camera module typically has at least two lenses and most of optical zoom functions are achieved by changing a distance between lenses and thus needs to extend out some distance from the surface of a portable electronic device, this means that the camera module can easily be damaged. Furthermore, the lenses are usually engaged with a barrel by a screw thread. Engagement between the lenses and the barrel must be very accurate in order to zoom precisely. Thus, the barrel and the lenses are difficult to manufacture to such rather exact specifications. If the screw thread associated with the barrel is damaged, the camera module will not zoom precisely.
What is needed, therefore, is a camera module, which has optical zoom function and overcomes the above-described problems.